1. Technical Field
The invention relates to a method for the analysis of isotope ratios, wherein at least one sample gas and/or at least one reference gas are supplied to at least one analytical device via at least one open split, the addition of a carrier gas also being possible. In addition, the invention relates to a device for supplying gases to at least one analytical device, particularly for carrying out the said method, comprising an open split which has a mixing zone and a waiting zone, wherein, in the waiting zone, capillaries for sample gas, carrier gas and/or reference gas and a capillary for removing the gases, particularly for supplying the gases to the analytical device, are arranged, wherein the capillaries can be moved into the mixing zone or to the mixing zone and back again.
2. Related Art
A special feature of devices for determining isotope ratios is that all components must be constructed in such a manner that no fractionations occur. These can occur, for example, wherever there is transport by diffusion.
An open split as interface between a mass spectrometer suitable for the analysis of isotope ratios (isotope mass spectrometer or IRMS) and a gas chromatography device is described, for example, in DE 43 33 208 A1. The analysis of CO2 and N2 when using helium as carrier gas is mentioned there. The quantity of the carrier gas supplied is variable so that the dilution of the two gases to be analyzed can be matched to one another. The volume of carrier gas is changed via suitable valves or by changing the position of capillaries immersed into the open split. To be able to correctly adjust the various gas streams and quantities in the sense of the results aimed for, the operating personnel requires great experience. The results of the analysis depend on the skill of the operating persons and fluctuate more or less randomly.